School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma, United States of America.
Center for Biomedical Engineering, University of Oklahoma, Norman, Oklahoma, United States of America.
PLoS One. 2014 Jan 8;9(1):e85192. doi: 10.1371/journal.pone.0085192. eCollection 2014.
Brain computer interface (BCI) is an assistive technology, which decodes neurophysiological signals generated by the human brain and translates them into control signals to control external devices, e.g., wheelchairs. One problem challenging noninvasive BCI technologies is the limited control dimensions from decoding movements of, mainly, large body parts, e.g., upper and lower limbs. It has been reported that complicated dexterous functions, i.e., finger movements, can be decoded in electrocorticography (ECoG) signals, while it remains unclear whether noninvasive electroencephalography (EEG) signals also have sufficient information to decode the same type of movements. Phenomena of broadband power increase and low-frequency-band power decrease were observed in EEG in the present study, when EEG power spectra were decomposed by a principal component analysis (PCA). These movement-related spectral structures and their changes caused by finger movements in EEG are consistent with observations in previous ECoG study, as well as the results from ECoG data in the present study. The average decoding accuracy of 77.11% over all subjects was obtained in classifying each pair of fingers from one hand using movement-related spectral changes as features to be decoded using a support vector machine (SVM) classifier. The average decoding accuracy in three epilepsy patients using ECoG data was 91.28% with the similarly obtained features and same classifier. Both decoding accuracies of EEG and ECoG are significantly higher than the empirical guessing level (51.26%) in all subjects (p<0.05). The present study suggests the similar movement-related spectral changes in EEG as in ECoG, and demonstrates the feasibility of discriminating finger movements from one hand using EEG. These findings are promising to facilitate the development of BCIs with rich control signals using noninvasive technologies.
脑机接口(BCI)是一种辅助技术,它可以解码人类大脑产生的神经生理信号,并将其转换为控制信号来控制外部设备,例如轮椅。挑战非侵入性 BCI 技术的一个问题是,从解码主要是大身体部位(如上下肢)运动的神经生理信号中获得的控制维度有限。据报道,在脑电(ECoG)信号中可以解码复杂的灵巧功能,即手指运动,而目前尚不清楚非侵入性脑电图(EEG)信号是否也具有足够的信息来解码相同类型的运动。本研究中,当通过主成分分析(PCA)对 EEG 功率谱进行分解时,观察到 EEG 中宽带功率增加和低频带功率降低的现象。这些与运动相关的频谱结构及其在 EEG 中手指运动引起的变化与之前 ECoG 研究中的观察结果以及本研究中的 ECoG 数据结果一致。使用运动相关的频谱变化作为特征,使用支持向量机(SVM)分类器对每个手指进行分类,从一只手的所有受试者中获得了 77.11%的平均解码准确率。使用同样获得的特征和相同的分类器,从 3 名癫痫患者的 ECoG 数据中获得的平均解码准确率为 91.28%。EEG 和 ECoG 的解码准确率均明显高于所有受试者的经验猜测水平(51.26%)(p<0.05)。本研究表明 EEG 中存在与 ECoG 相似的运动相关频谱变化,并证明了使用 EEG 从一只手区分手指运动的可行性。这些发现有望促进使用非侵入性技术开发具有丰富控制信号的 BCI。